A report into the service provided by the NHS in London has described it as "cash strapped, fragmented health care and unravelling".
The People's Inquiry, commissioned by the Unite union, found the public have "no real voice" in health care because of a lack of an overarching strategy.
It called for a London strategy-making body, a review of ambulance services and midwife-led maternity units.
Health minister Dr Daniel Poulter said key decisions are made by doctors.
"I always take these reports with a pinch of salt, particularly when it's Unite the union who are backing the report," he said.
"But what we have seen is that by the improvements the government has been putting into the NHS...it is doctors and nurses who make the decisions about delivering frontline patient care."
NHS England, the public body set up to oversee the budget, planning, delivery and day-to-day operation of the NHS in England, said it had already given a "call to action" on many of the issues raised by the report.
Unite is one of the largest British and Irish trade unions for workers in sectors ranging from transport to education.
Last April, NHS London was replaced by 32 Clinical Commissioning Groups (CCG)- aimed at designing local health strategies.
But, the report said, that had "fragmented" commissioning and its authors called for the formation of a London-wide strategic health authority which would involve local people.
A "review of funding" was also needed, it claimed, as the £10bn annual budget for London's CCGs did not account for inflation and rising costs.
The report also demands "an urgent review of emergency ambulance services", "further research into the clinical safety of stand-alone midwife-led units" and a "moratorium on any further reductions in mental health provision".
Roy Lilley, the chair of the inquiry, said: "I was truly shocked at the unravelling services, the complexity and the enormity of the difficulty involved in trying to plan and deliver cohesive, integrated services from the wreckage of a fragmented care landscape."
He added that the proposed financial restraint for the next seven years was "unsustainable without serious damage to the quality and availability of NHS services".
Unite's Regional Secretary for London, Pete Kavanagh, said the Health and Social Care 2012 Act had "drained the NHS of an essential £3bn which ought to have gone on patient care and imposed horrendous and needless upheaval on the service".
But Dr Andrew Mitchell, medical director of NHS England, said they had highlighted the financial shortfall months ago and they needed to "empower patients so that they can gain access to services when they need them in community settings, rather than depending upon hospitals."
He added that the current leadership provided by the CCGs would be a "bedrock for a sound strategic leadership for the future".